4: Bioenergetics Flashcards
what is the word and symbol equation for photosynthesis?
water + carbon dioxide -> oxygen + glucose
6H2O + 6CO2 -> 6O2 + C6H12O6
what kind of equation is photosynthesis? why?
endothermic reaction - energy is transferred from the environment to the chloroplasts by light
what three factors affect rate of photosynethesis?
light, temperature and carbon dioxide
how does temperature affect the rate of photosynthesis?
lower the temperature, less kinetic energy particles have, resulting in fewer successful collisions occurring over a period of time; increasing temperature increases kinetic energy of particles, increasing the likelihood of collisions between reactants and enzymes which results in the formation of products;
at higher temperatures, enzymes can be denatured - this reduces the overall rate
how does light affect the rate of photosynthesis?
more light a plant receives, faster the rate of photosynthesis - light energy is required for the reaction to take place; this trend will continue until some other factor required for photosynthesis prevents the rate from increasing further because it is now the limiting factor
how does CO2 concentration affect the rate of photosynthesis?
more carbon dioxide that is present, the faster the reaction can occur; this trend will continue until some other factor required for photosynthesis prevents the rate from increasing further because it is now the limiting factor
how does the amount of chlorophyll affect the rate of Ps?
they contain the pigment chlorophyll which absorbs light energy for photosynthesis; more chloroplasts a plant has, faster the rate of photosynthesis
what is inverse square law?
shows the relationship between light intensity and distance - as the distance increases the light intensity decreases. - inversely proportional to each other
what is the equation for light intensity?
light intensity = 1/distance squared
how can people increase crop yield?
keep plants in a greenhouse - no shades so mx. amount of light, also glass traps heat so temp is not a limiting factor, also makes it easier to protect them from pests and diseases; artificial lights so photosynthesis can occur at night or when there is less sun light; a heater can burn paraffin to release CO2; watering system to keep plants well watered; ventilation so plants don’t get too hot
what are the uses of glucose?
respiration; converted into insoluble starch for storage in the stems, leaves and roots; to produce fat or oil for storage (especially in seeds); to produce cellulose, which strengthens the cell wall; combined with nitrate ions to produce amino acids for protein synthesis
what kind of reaction is respiration?
exothermic reaction - continuously occurring in living cells; releases energy
why do organisms need energy?
chemical reactions - to build larger molecules from smaller molecules; muscle contraction - movement;
keeping warm - maintain constant temp. for enzymes
what is the word and symbol equation for aerobic respiration?
glucose + oxygen -> carbon dioxide + water
C6H12O6 + 6O2 -> 6CO2 + 6H2O
what is anaerobic respiration? when does it occur?
incomplete breakdown of glucose into lactic acid to release energy; occurs when the body can’t supply enough oxygen for aerobic respiration, e.g. during exercise
what is the word and symbol equation for anaerobic respiration?
glucose -> lactic acid (+ less energy released)
where does aerobic respiration occur? how has this place adapted to make the reaction more efficient?
mitochondria; has a highly folded inner membrane to provide a large s.a. for the enzymes involved in respiration
why is lactic acid produced in anaerobic respiration?
the oxidation of glucose is incomplete so less energy released
what is the equation for anaerobic respiration in plants?
glucose -> CO2 + ethanol (+ less energy released)
what is anaerobic respiration in plants used for?
in yeast cells it is called fermentation; important in the baking industry (carbon dioxide makes dough rise) and brewing industry (as ethanol = alcohol)
why is lactic acid bad?
it causes muscle fatigue - muscles stop contracting efficiently & cramps
why does heart rate increase in response to exercise?
to allow blood to be pumped faster to working muscles - blood carries O2 and C6H12O6 which are required for respiration
why do arteries supplying blood to muscles dilate in response to exercise?
so more blood can get to and from muscle cells, transporting reactants and products of RESP
why does breathing rate increase in response to exercise? why do we cont. to breathe heavily after exercise?
enables more O2 to be used to convert the lactic acid back to glucose; enables faster removal of CO2 - acidic gas, if left this would build up and alter pH, could denature enzymes
why does depth of breathing increase in response to exercise?
allows more O2 to be taken in w each breath for respiration and to increase removal of CO2
why does body temp. increase in response to exercise?
respiration releases energy, some is lost as heat energy
what is oxygen debt?
the amount of extra oxygen needed to react w accumulated lactic acid to remove it
where does lactic acid go?
increased blood supply to muscles removes lactic acids and transports it to the lungs, where it is converted back to glucose (oxygen required)
what is glycogen? why do we need it?
polymer of glucose for storage; stored in muscle cells and liver; can be converted by muscle cells back to glucose when there is not enough for respiration
what is metabolism?
the sum of all the chemical reactions in a cell or the body
give examples of metabolic reactions.
respiration; polymerisation of e.g. starch, glycogen, cellulose, lipids/fats; polymerisation in plants of amino acids then proteins; break down of excess protein to urea by liver (filtered by kidneys)
what is metabolism rate?
the rate all the chemical reactions in your body occur
what factors affect your metabolic rate?
what you have inherited from your parents via genetics; your age; your sex; the proportion of muscle to fat in your body (muscles have a higher metabolic rate)
